Audio Database

The

SANSUI AU-D707F
108,000yen(1980 release)

Description
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The Integrated Amplifier which carries the super feed-forward system newly developed as a technology of transcending the threshold of NFB.

In order to compensate with the NFB technology adopted with the conventional amplifier and to reduce distortion more, the super feed-forward system developed uniquely is carried.
This circuitry is a circuitry which used as the base feed-forward theory devised by Mr. H.S. Black in 1928, and is at an SANSUI,Although the likelihood of practical use was explored in 1975, a Tips called combined use of a NFB technology was carried out in its hands in frustration of what will run and suspension and make an issue of the job restart of the research continuously in 1978, and 1980, and this was completed at last.
Many problems which are the circuitries in which a chisel is possible theoretically, and should be overcome although this feed-forward circuitry takes out only a distorted component from the HARASHIN number and it was said with the output by making it into an opposite phase that a synthetic and distortion are canceled were made into the theory of a phantom. Then, the structure which connected the strength of both NFB and feed forward with the super feed-forward system and with which it united is adopted.
NFB is also making an additional post of the role which mainly operates to a low-pass distorted modification, and takes out the opposite phase distortion for feed forward hold. Moreover, the error collection amplifier for feed forward is formed, and also full use of a computer technology is made, and the distorted removal is enabled over the wide band by developing the summing network of the output which can perform distorted cancellation also to 2 pole build-out.
While little design of the amount of NFB is attained and the stability of amplifier increases by this super feed-forward system, TIM distortion is mostly made to zero.

The diamond differential circuit adopted as the AU-D series is carried.
A diamond differential circuit considers it as the dual complimentary differential interconnection which combined 2 sets of differential circuits up and down, and is carried in the predrive stage. This is sending the required drive electric current into the power stage faithfully also to the transitional and complicated peek input like a music signal.
Moreover, by 2 pole phase-compensation circuitry, the operating range of NFB was expanded and the high-speed responsibility which was excellent to the input signal is realized.

The three-dimensional solid product line is performed and the signal path of the shortest distance is completed at the same time it puts simple & straight-ization into practice and makes the fluence of a signal a very short-haul and simple.
Furthermore, the pattern from an input to an output is able to develop by ideal hand-held on a printed circuit board stream composition along with the fluence of a circuit diagram by having adopted the heat pipe for a heat dissipation. For this reason, in the case where the conventional heat sink is used, the setups which brings the difficult power stage and the driver stage close could be realized, and also the adjacency setting of the two transistors which constitute a push pull output circuit could be carried out, and leading about of the wire rod near [ through which a large electrical power flows ] an output transistor is eliminated.
Moreover, with a twin relay speaker switchpoint, Speakers A and B are changed and leading about of an output line is prevented.

The know-how acquired by AU-D907Limited is supplied, and the design which cannot receive influences of a magnetic distortion including a substrate or a chassis structure easily, such as adopting a wood bonnet, a bronze plating screw, and NM element in large quantities, is put into practice.

Tone amplifier is excluded and it has 2 amplifier stream compositions of a high gain equalizer amplifier and power amplifier.
An equalizer uses the Dual FET of low-noise high gm for the first rank, and is considering it as the push pull drive pure complimentary SEPP output by two steps of differentials, and an electric-current differential with a current mirror.
And DC servo is adopted in order to remove an output capacitor, expecting a stabilization of DC area.

The newly developed linear servo regulator is employed as the power-source part only for an equalizer.
Since this stabilizing supply can perform the response stabilized also to the transitional load intensity by sending a fixed bias current in a circuitry, it makes the always clean and stable powering possible.

MC head amplifier which adopted the symmetrical circuitry of two steps of differentials as MC cartridges is carried.
With this MC head amplifier, a High position (0.1mV/100 ohms) and a Low position (0.25mV/100 ohms) can be chosen so that it can respond also to the size of the output by the difference in the type of a cartridge by preparing an input gain changeover switch.

A power-source part considers it as a right-and-left independent 2 power-source scheme, and has the 2 coil 2 power-source stream composition.
Moreover, the high speed capacitor with the flattery nature which is a low-impedance type by low scaling-factor etching, and was excellent also in transitional charge and discharge is used for a block capacitor.
Furthermore, first recovery diode with a quick switching speed is adopted as rectifier diode, and the responsibility of a regulation is raised.

The simple tone control circuit which consisted of CRs is carried.
Since it is a simple scheme without amplification elements, such as an equalizer and power amplifier,The volume location is -6dB-0dB (at the time of full power) with the design which is not effective in a tone control, and a saturation is not started more than the amplification degree of amplifier at the time of full power like before.

A Subsonic Filter, a supersonic filter, 2 circuitry tapes monitor, the recording selector / copy function, the audio muting, the balance control, the input selector with Idi Kater, etc. are carried.

There were two kinds, the black model of a rosewood tone bonnet and the silver model of a white oak tone bonnet.

Silver

Rating of a mode
Form Super feed-forward &DD/DC amplifier
<Power amplifier part>
Effective output 95W+95W (8 ohm, 10Hz - 20kHz, THD 0.005%)
95W+95W (8 ohm, 1kz, THD 0.003%)
THD (at the time of 10Hz - 20kHz, and an effective output) 0.005% or less
Cross modulation distortion (60Hz:7kHz=4:1, SMPTE) 0.008% or less
Output bandwidth (IHF, both channel operation, THD 0.02%) 5Hz - 80kHz
Dumping factor (new IHF, 20Hz - 20kHz) 100 (8ohm)
Frequency characteristic (1W) DC-300kHz+0 -3dB
SN ratio (A network) 110dB or more
Envelope distortion Below a limit of measurement
TIM distortion (the Sqwtooth method) Below a limit of measurement
Slew rate }200v/microsec (8ohm)
Inside slew rate }300v/microsec (8ohm)
Rise time 0.8microsec
<Preamplifier part>
Input sensitivity/input impedance (1kHz) Phono1, 2 man-month:2.5mV /, 47kohm
Phono1, 2 MC (high/low): 100 microvolts, 250 microvolts/100 ohm
Tuner, AUX, Tape Play1, 2:250mV / 27kohm
Phono maximum permissible input (1kHz, THD 0.01%) MM:200mV
MC:25mV
An Output voltage/impedance (1kHz) Tape Rec: 250mV (47kohm)/600ohm
THD Phono1, 2 man month: 0.005% or less (20Hz - 20kHz, 5V)
RIAA deflection (man month) 20Hz-20kHz}0.2dB
SN ratio (A network) Phono1, 2 man month: 90dB or more
Phono1, 2 MC: 74dB or more
Phono input conversion noise
(A network, a short circuit)
Phono1, 2 man-month:-142dBV
Phono1, 2 MC:-154dBV
Channel separation Phono1, 2 man month: 60dB or more
Phono1, 2 MC: 50dB or more
Tuner, AUX, Tape Play: 80dB or more
Tone control Bass: +6--8dB (50Hz)
Treble: }6dB (10kHz)
Tone selector Bass: 150Hz, 300Hz
Treble: 3kHz, 6kHz
Filter Low: 16Hz (-3dB, 6 dB/oct)
High: 20kHz (-3dB, 6 dB/oct)
Audio muting -20dB
<Synthesis>
Power dissipation (Electrical Appliance and Material Control Law) 250W
Dimensions Width 445x height 163x depth of 403mm
Weight 14.0kg